Subsarcolemmal and intermyofibrillar mitochondria proteome differences disclose functional specializations in skeletal muscle |
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Authors: | Rita Ferreira Rui Vitorino Renato M P Alves Hans Joachim Appell Scott K Powers José Alberto Duarte Francisco Amado |
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Institution: | 1. QOPNA, Chemistry Department, University of Aveiro, Aveiro, Portugal;2. CIAFEL, Faculty of Sport Sciences, University of Porto, Porto, Portugal;3. Department of Physiology and Anatomy, German Sport University, Cologne, Germany;4. Department of Applied Physiology and Kinesiology, University of Florida, Gainesville, FL, USA |
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Abstract: | Skeletal muscle is a highly specialized tissue that contains two distinct mitochondria subpopulations, the subsarcolemmal (SS) and the intermyofibrillar (IMF) mitochondria. Although it is established that these mitochondrial subpopulations differ functionally in several ways, limited information exists about the proteomic differences underlying these functional differences. Therefore, the objective of this study was to biochemically characterize the SS and IMF mitochondria isolated from rat red gastrocnemius skeletal muscle. We separated the two mitochondrial subpopulations from skeletal muscle using a refined method that provides an excellent division of these unique mitochondrial subpopulations. Using proteomics of mitochondria and its subfractions (intermembrane space, matrix and inner membrane), a total of 325 distinct proteins were identified, most of which belong to the functional clusters of oxidative phosphorylation, metabolism and signal transduction. Although more gel spots were observed in SS mitochondria, 38 of the identified proteins were differentially expressed between the SS and IMF subpopulations. Compared to the SS mitochondrial, IMF mitochondria expressed a higher level of proteins associated with oxidative phosphorylation. This observation, coupled with the finding of a higher respiratory chain complex activity in IMF mitochondria, suggests a specialization of IMF mitochondria toward energy production for contractile activity. |
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Keywords: | 2‐D BN‐PAGE/MS/MS 2‐DE/MS/MS Animal proteomics BN‐PAGE Density gradient purification Mitochondrial subpopulations |
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